U.S. patent number 6,572,199 [Application Number 10/115,800] was granted by the patent office on 2003-06-03 for flanged tubular axle shaft assembly.
This patent grant is currently assigned to General Motors Corporation. Invention is credited to Steve W Creek, Tim P Raleigh.
United States Patent |
6,572,199 |
Creek , et al. |
June 3, 2003 |
Flanged tubular axle shaft assembly
Abstract
A flanged axle shaft assembly includes a shaft having a tubular
wall and an open end, a flange hub having a central opening fitted
over the shaft and secured to the open end, and an end wedge
secured in the open end and urging the shaft wall into compressive
engagement with the flange hub opening to provide for transmission
of forces between the shaft and the flange hub. In a preferred
method of assembly, the shaft is formed with a flared inner end
stop against which the hub flange is mounted about the shaft.
Forcing the end wedge into the shaft inner end expands the shaft
wall into a characterized, such as splined, surface of the hub
central opening to provide a high torque mechanical driving
connection. The hub flange and a head of the end wedge are
preferably also laser welded to the shaft.
Inventors: |
Creek; Steve W (Shelby
Township, MI), Raleigh; Tim P (Macomb Township, MI) |
Assignee: |
General Motors Corporation
(Detroit, MI)
|
Family
ID: |
22363453 |
Appl.
No.: |
10/115,800 |
Filed: |
April 3, 2002 |
Current U.S.
Class: |
301/124.1;
301/126; 301/132 |
Current CPC
Class: |
B60B
35/08 (20130101); B60B 35/121 (20130101); B60B
2310/3026 (20130101); B60B 2360/102 (20130101) |
Current International
Class: |
B60B
35/00 (20060101); B60B 35/08 (20060101); B60B
035/00 () |
Field of
Search: |
;301/124.1,125,126,132,35.53,112,117,111.01,111.02,111.03,111.04,111.07
;403/359 ;29/525,515,516,522.1 ;188/218XL |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Morano; S. Joseph
Assistant Examiner: Nguyen; Long Bao
Attorney, Agent or Firm: Hargitt; Laura C.
Claims
What is claimed is:
1. A flanged axle shaft assembly comprising: a shaft having a
tubular wall and an open end; a flange hub having a central opening
fitted over the shaft and secured to the open end; and an end wedge
secured in the open end and urging the shaft wall into compressive
engagement with the flange hub opening to provide for transmission
of forces between the shaft and the flange hub wherein the end
wedge extends into the shaft and engages the interior of the
tubular wall axially inward of the flange hub to provide solid
support for a wheel bearing engagable with the exterior of the
shaft.
2. A flanged axle shaft assembly comprising: a shaft having a
tubular wall and an open end; a flange hub having a central opening
fitted over the shaft and secured to the open end; and an end wedge
secured in the open end and urging the shaft wall into compressive
engagement with the flange hub opening to provide for transmission
of forces between the shaft and the flange hub wherein the shaft is
connected by laser welding to the flange and to the end wedge.
3. A flanged axle shaft assembly comprising: a shaft having a
tubular wall and an open end; a flange hub having a central opening
fitted over the shaft and secured to the open end; and an end wedge
secured in the open end and urging the shaft wall into compressive
engagement with the flange hub opening to provide for transmission
of forces between the shaft and the flange hub wherein the open end
of the shaft has an outwardly flared portion and the flange hub has
a hub portion engaging an axially inner surface of the flared
portion and wherein the end wedge has a head engaging an axially
outer surface of the flared portion.
4. An assembly as in claim 3 wherein the outwardly flared portion
of the shaft is laser welded to the hub portion and the end
wedge.
5. An assembly as in claim 4 wherein an axially inner end of the
hub is also laser welded to the shaft.
6. An assembly as in claim 5 wherein the flange hub central opening
includes a characterized inner surface having recesses into which a
portion of the shaft wall is deformed by the end wedge for
increasing the capability of force transmission between the tube
and the hub.
7. An assembly as in claim 6 wherein the characterized inner
surface includes spline-like projections.
8. A flanged axle shaft assembly comprising: a shaft having a
tubular wall and an open end; a flange hub having a central opening
fitted over the shaft and secured to the open end; and an end wedge
secured in the open end and urging the shaft wall into compressive
engagement with the flange hub opening to provide for transmission
of forces between the shaft and the flange hub wherein the shaft
has an inner end axially opposite to the open end, said inner end
being reduced in diameter and including external means for
connecting the shaft to an axle drive assembly.
9. An assembly as in claim 8 wherein said external means include
splines for connecting with the drive assembly.
10. A method of making a tubular axle shaft assembly comprising the
steps of: providing a high strength low alloy steel tubular shaft
having a wall with adequate strength for use as an axle shaft;
assembling a central opening in a preformed flange hub with a close
fit on to an open outer end of the shaft; forcing an end wedge into
the open outer end of the shaft to expand the wall of the shaft
outer end into force transmitting engagement with an inner surface
of said central opening to provide a force transmitting mechanical
connection; and fixing the flange hub and the end wedge in position
at the inner end of the tubular shaft.
11. A method as in claim 10 wherein the fixing step includes laser
welding the flange hub and the end wedge to the tubular shaft.
12. A method as in claim 11 including, prior to the fixing step:
expanding the shaft diameter adjacent the outer end and flaring the
outer end to form an end stop; positioning the flange hub against
an inner side of the end stop; and positioning a head of the end
wedge against an outer side of the end stop.
13. A method as in claim 10 including providing a characterized
inner surface in the flange hub opening having projections and
recesses against which the tubular shaft wall is expanded to make
said mechanical connection.
14. A method as in claim 10 including reducing the diameter of the
shaft inner end to provide an increased wall thickness and forming
retaining and drive connectors on the inner end for connection of
the shaft to an axle drive assembly.
Description
TECHNICAL FIELD
This invention relates to axle shafts for vehicles and more
particularly to an assembly having a tubular axle shaft with a
flange member fixed at the axially outer end of the shaft.
BACKGROUND OF THE INVENTION
It is known in the art relating to vehicle axle shafts to form such
shafts as one piece forgings to transmit the considerable torque
and loads applied at the wheel end of an axle housing. It is also
known to utilize two piece axle shafts where a solid shaft is
friction welded to a flange hub. Friction welding of a tube
assembly to a flange hub has also previously been developed.
SUMMARY OF THE INVENTION
The present invention provides an improved form of axle shaft
assembly in which a mechanical connection is provided between a
tubular shaft and a flange hub mounted on an axially outer open end
of the shaft. The assembly includes an end wedge forced into the
open end of the shaft and expanding the wall of the shaft to
compress the wall into engagement with a central opening in the
flange hub to provide for transmission of torque and axial forces
between the flange hub and the shaft.
In a preferred embodiment, the outer end of the shaft is expanded
and provided with a flared end. The flange hub includes a hub
portion which is fitted tightly onto the expanded portion of the
shaft and against the flared end. Preferably the flange hub central
opening includes a characterized surface with spline like features
into which the shaft wall is expanded by insertion of the end wedge
so that a mechanical torque transmission connection is provided by
expansion of the tube into the recesses between the spline like
projections. Other forms of characterized surfaces may also be
utilized.
The end wedge preferably extends inward of the flange hub to
provide a solid support for the expanded portion of the shaft on
which a wheel bearing is mounted. The shaft is preferably laser
welded to the flange hub at the inner and outer edges of the hub
portion and to a head of the end wedge adjacent the outer end of
the hub portion.
The inner end of the shaft may be reduced in diameter, splined and
provided with additional features for attaching the inner end to an
axle drive assembly, such as a differential gear set. The inner end
may be hollow with thickened wall sections or may be compressed to
a substantially solid end portion.
The invention provides a novel design and method for mechanically
attaching a flange hub to a tubular axle shaft including laser
welding of the flange hub to the shaft. Benefits of the design and
method include:
1. Use of a generally flat flange hub which is more easily
manufactured than conventional one piece axle shaft forgings.
2. Significant weight reduction of the axle due to variable wall
thickness tubing which is utilized in place of solid bar stock.
3. Use of a mechanical joint between the flange hub and the axle
shaft tube formed in part by an end wedge which deforms the axle
tube into spline like features or other characterized surface
features on the inner diameter of the flange hub central
opening.
4. The use of laser welding for additional positive attachment of
the shaft tube to the flange hub and the end wedge.
5. Reduced heat treating cycle time due to the lower mass of the
tube and reduced internal stresses from the laser welding
process.
These and other features and advantages of the invention will be
more fully understood from the following description of certain
specific embodiments of the invention taken together with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is an isometric view of a flanged axle shaft assembly formed
according to the invention;
FIG. 2 is a cross-sectional view of the assembly of FIG. 1
illustrating the manner of installing the preformed flange hub on
the hollow axle tube; and
FIG. 3 is an enlarged cross-sectional view of the outer end of the
shaft assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in detail, numeral 10 generally
indicates a flanged axle shaft assembly according to the invention.
Assembly 10 includes a tubular shaft 12, a flange hub 14 mounted on
an open outer end 16 of the shaft and an end wedge 18 secured in
the open end 16. The end wedge 18 expands the tubular wall 19 of
the shaft 12 into compressive engagement with a central opening 20
in the flange hub 14 to provide a mechanical connection that
supports transmission of substantial torsional and axial forces
between the shaft and the flange.
In a preferred embodiment, the shaft tube is produced from drawn
over mandrel high strength low alloy steel tubing which is
available and used for other purposes. The shaft tube is formed
with adequate wall thickness and strength to meet vehicle loading
requirements. An inner end 22 of the shaft is reduced in diameter
to provide a thickened wall and is preferably provided with
attachment and drive features including, for example, splines 24
and a locking groove 26. If desired, the inner end 22 may be
sufficiently reduced in diameter to form an essentially solid inner
end for connection of the shaft 12 to an axle drive assembly such
as a differential bevel drive gear, not shown.
The axially outer end 16 of the shaft may be expanded to a larger
diameter than the central portion of the tubular shaft 12 between
the inner and outer ends 22, 26. A portion of the outer end 16 is
flared radially outward at 28 to provide an end stop.
The flange hub 14 may be forged or otherwise formed and includes a
generally flat disk portion 30 connecting radially inwardly with an
enlarged hub 32 having the central opening 20. The interior of the
opening 20 is preferably provided with a characterized surface
having a desired degree of roughness or characterized features
including projections and alternate recesses as desired. In the
preferred embodiment the characterized surface is formed with
spline like projections 36, which extend inward and define groove
like recesses 38 between the projections 36 as shown in FIG. 3. An
axially outer end 40 of the hub 32 is configured to closely engage
the flared end stop 28 of the tubular shaft 12 and is preferably
secured to the shaft by laser welding at 42. An axially inner end
44 of the hub 32 is preferably also laser welded to the tubular
shaft at 46. The flat disk portion 30 of the flange hub 14 includes
openings 48 in which wheel studs are subsequently installed for the
attachment of a wheel to the finished axle shaft assembly 10.
The end wedge 18 is formed with an extended near cylindrical body
50 which may be slightly wedge shaped, having a smaller diameter at
its inner end than at the outer end adjacent an enlarged head 52.
The outer periphery of the head 52 is preferably also laser welded
to the flared end stop at 54.
Upon installation of the end wedge 18, the wedge expands the shaft
wall at the outer end 16 of the shaft 12 and forces the outer
surface of the tube wall into the recesses 38 between the spline
like projections 36 in the central opening 20 of the hub 32. The
flange hub 14 and the shaft 12 are thus mechanically interlocked at
a joint which provides a high level of capability to transmit
torque delivered between the axle shaft and the attached hub.
Manufacture of the preferred embodiment of tubular axle shaft
assembly 10 is accomplished as follows. A high strength low alloy
steel tube having walls with adequate strength for use as an axle
shaft is modified by reducing the diameter of an inner end 22 and
optionally expanding the diameter of an outer end 16. The outer end
is terminated by an outwardly flared end stop 28.
A forged or otherwise formed flange hub 14 is then installed on the
shaft 12 by sliding the flange hub over the small inner end 22 of
the shaft in the direction of arrow 56 until the hub portion 32
engages the flared end stop 28 of the shaft. The central opening 20
of the flange hub includes spline like projections 36 with
alternating recesses 38 that engage the outer surface of the
enlarged outer end of the shaft.
The end wedge 18 is then forced into the hollow interior of the
enlarged outer end 40 of the shaft so that the body 50 of the wedge
extends within the shaft and the head 52 of the wedge engages the
outer side of the flared end stop 28 of the shaft. As the body 50
of the end wedge is inserted into the shaft, it expands the wall of
the outer end 16 into engagement with the splines 36 and recesses
38 of the hub central opening 20 to provide a high torque
mechanical connection. The body 50 of the end wedge extends through
the hub opening 20 into an adjacent expanded portion of the outer
end 40 of the shaft and provides a solid support for the walls of
the shaft in this region for the subsequent installation of a wheel
bearing on the outer surface of the enlarged outer end of the
tube.
The shaft assembly is then preferably fastened together by laser
welding of the tubular axle shaft to opposite ends of the flange
hub and to the head of the end wedge. The assembly is then heat
treated followed by machining of necessary portions of the
assembly, such as the flat disk portion of the flange hub and the
bearing mounting surface or journal of the axle shaft enlarged
outer end 16. The splines 24 and locking groove 26 may also be
machined or otherwise formed, as by rolling, at the shaft inner end
at that time.
While the invention has been described by reference to certain
preferred embodiments, it should be understood that numerous
changes could be made within the spirit and scope of the inventive
concepts described. Accordingly, it is intended that the invention
not be limited to the disclosed embodiments, but that it have the
full scope permitted by the language of the following claims.
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